1. Field of the Invention
The present invention relates to an apparatus for exchanging metal molds for a molding machine employing metal molds, such as a press molding machine, an injection molding machine and so on. Such apparatus includes a mold carriage capable of mounting thereon at least two metal molds for the molding machine, said machine performing the molding using one of these molds under exchange with one another. Such apparatus also includes a mold transfer and exchange-transport truck capable of effecting the transport of the metal mold to be exchanged through the course between said carriage and the molding machine and to give and receive the metal mold horizontally.
2. Description of the Prior Art
In order to realize automation and energy economization in the operation of exchange of metal molds for a press molding machine such as the one disclosed in the Japanese Patent Publication Sho 55-4853, the inventors had been attempting to develop an apparatus for exchanging metal molds. The apparatus for exchanging metal molds previously proposed as mentioned above had the construction, in which a mold transfer and exchange-transport truck unit was arranged on one side of the press molding or on a mold storage rack which serves as a metal mold carriage, wherein said transfer and exchange-transport truck unit was provided with a conveying means capable of effecting to draw the metal mold out onto said transport truck or to push the metal mold on the truck forward onto the press molding machine. Thus, the apparatus consisted of a sprocket that serves as the driving wheel connected to the driving motor on one side of said transfer and exchangetransport truck in a bearing relation so as to permit rotation in a vertical plane and a guide rail formed in a box-shaped profile laid down on said transfer and exchange-transport truck which extends horizontally and tangentially to said sprocket. A chain, which is one embodiment of the above mentioned elongated member and which is permitted to slide inside said guide rail, is wound around said sprocket and arranged at the front end of said chain is a hook projecting upwards through the upper face of the guide rail for engagement with said metal mold, whereby the metal mold set in the molding machine or the one stored in the storage rack can be transferred onto said transfer and exchange-transport truck or vice versa, by rotating said sprocket to operate the chain.
Since the apparatus for exchanging metal molds mentioned above can also be used for injection molding machines, the apparatus according to the present invention is referred to hereinafter in this specification only as apparatus for a molding machine.
The conveying means consisting of an elongated member, a guide rail and a driving wheel mentioned above had an advantage that it permits the arrangement to be designed in smaller size, since the elongated member can be housed more easily by the yieldability thereof, notwithstanding that the length of the conveyance became greater, as compared with the conveying means employing a piston-cylinder combination. In addition, the transfer and exchange-transport truck was able to be handled as one having an apparently smaller size on transporting the metal mold, notwithstanding that the conveyance length on the transfer and exchangetransport truck unit was increased when an extension rail was employed.
In the mold transport truck unit of the previous proposal, an extension rail is employed for bringing the metal mold over to the molding machine in such a manner that the guide rail is extended straight by said extension rail to the molding machine so as to permit the hook for engagement with the metal mold to reach the molding machine. Heretofore, the setting of such extension rail had to be effected manually and has been one of the obstacles for realizing the automation of the mold exchange. In considering an automatic setting of such an extension rail, a technique that comes first into mind is one in which the so employed extension rail is held up while it is out of use. However, such a manner of holding up the extension rail may require an additional means for preventing the falling off thereof, resulting in a complication of the total construction. On the other hand, if the so assembled extension rail hangs down while it is out of use, the height of the transport truck will be restricted in accordance with the size of the metal mold, whereby the length of the extension rail will also be limited.